1. Field of the Invention
The present invention relates to a plasma display panel.
2. Discussion of Related Art
Plasma display panels (PDPs) refer to flat display panels that display images using a gas discharge phenomenon. Such display panels may provide excellent display capabilities, e.g., large-capacity display, high brightness, high contrast, low image sticking, a wide-range of viewing angle, and so forth, and a thin/large screen, as compared to conventional cathode ray tube (CRT) displays.
With reference to FIG. 1, a conventional plasma display panel (PDP) 100 includes a first substrate 101, a second substrate 102, sustain electrodes 120, a first dielectric layer 105, a protective layer 106, address electrodes 107, a second dielectric layer 108, barrier ribs 109, and red, green, and blue phosphor layers 110. Each of the sustain electrodes 120 includes an X electrode 103 and a Y electrode 104 arranged in a pair, which are alternately arranged at a surface of the first substrate 101. The first dielectric layer 105 covers (or encases) the X electrode 103 and the Y electrode 104. The protective layer 106 is formed on a surface of the first dielectric layer 105. A corresponding one of the address electrodes 107 is arranged at a surface of the second substrate 102 to cross the X electrode 103 and the Y electrode 104. The second dielectric layer 108 covers (or encases) the address electrode 107. The barrier ribs 109 are installed between the first substrate 101 and the second substrate 102 and define a discharge space. The red, green, and blue phosphor layers 110 are coated on sides of the barrier ribs 109 and on a surface of the second dielectric layer 108.
The first substrate 101 and the second substrate 102 are formed to face each other with a gap therebetween. The gap formed between the first substrate 101 and the second substrate 102 is filled with a mixture of Ne+Xe gas or a mixture of He+Ne+Xe gas at a pressure level that may be predetermined (for example, 450 Torr).
In the PDP 100 having the construction as described above, when an electric signal is applied to the Y electrode 104 and the corresponding one of the address electrodes 107, a discharge cell is for an emission. When the electric signal is alternately applied to the X and Y electrodes 103 and 104, a visible ray is emitted from the phosphor layers 110 coated in the selected discharge (or emission) cell to display a static image and/or a moving image.
The X and Y electrodes 103 and 104 and the address electrodes 107 are driven by a circuit.
The protective layer 106 in the PDP 100 has three functions.
First, the protective layer 106 functions to protect an electrode and a dielectric material. That is, a discharge may be generated in an electrode only structure or in a dielectric material and electrode only structure. Here, when the discharge is generated in the electrode only structure, it may be difficult to control a discharge current. When the discharge is generated in the dielectric material and electrode only structure, because the dielectric material can be damaged due to a sputtering etch, the dielectric material should be coated with a protective layer, which is resistant to plasma ions.
Second, the protective layer 106 functions to reduce a discharge start voltage. A physical quantity directly related to the discharge start voltage is a secondary electron emission coefficient of a material that is used to form the protective layer 106 for plasma ion resistance. The more the secondary electron coefficient of the protective layer is, the less the discharge start voltage is. Accordingly, the greater the secondary electron emission coefficient of a material forming a protective layer is, the better a characteristic thereof is.
Finally, the protective layer 106 functions to reduce a discharge delay time. The discharge delay time is a physical quantity that refers to a time after which a discharge occurs from an applied voltage, and may be derived from a sum of a formation delay time and a statistical delay time. As the discharge delay time is reduced, the addressing speed is increased, thereby allowing for the use of a single scan, reducing a scan driver cost, and/or increasing the number of available sub fields. Also, the reduction of the discharge delay time can also provide the PDP 100 with improved luminance and/or image quality.
When the PDP 100 is driven, a voltage is applied into the panel and discharge gas injected therein is electrolyzed to form plasma.
However, when the plasma is generated, positive ions in the plasma periodically collide with the first substrate 101 by an alternating current voltage applied to the X and Y electrodes 103 and 104 of the first substrate 101.
The protective layer 106 may be etched (or damaged) by the ion shock, which is positioned at a peripheral part of the X and Y electrodes 103 and 104 of the first substrate 101.
When the protective layer 106 is etched, it interrupts a normal discharge in the panel, thereby reducing the lifespan of the PDP 100.
FIG. 2 is a picture showing an etching of a protective layer in a conventional plasma display panel. As shown in FIG. 2, an etch 130 of the protective layer 106 due to an ion shock mainly occurs at regions near an ITO electrode 103b and a bus electrode 104a of the X and Y electrodes 103 and 104.